Work supporting mechanisms for blindstitch sewing machines



Feb. 24, 1959 F. PARRY ETAL WORK SUPPOR TING MECHANISMS FOR BLINDS T ITCH SEWING MACHINES Filed May 3, 1956 2 Sheets-Sheet 1 m'wmozc F rank Parry and BY v Earl F. Dunn W y- 6 5- 44 TTORNEY WITNESS Feb. 24, 1959 F. PARRY ET'AL WORK SUPPORTING MECHANISMS FOR BLINDS TITCH SEWING MACHINES I Filed May 5, 1956 2 Sheets-Sheet 2 uvmvrox Frank Parry and TTORNEY av I Earl R Dunn W9 W/TNESS Uniwd S a e Patent WORK SUPPORTING FOR.

BLINDSTI'ICH SEWING MACHINES Frank Parry, Trumbull, and Earl F. Dunn, Devon, Conn., assignors to The Singer Manufacturing Company, Elizabeth, N J., a corporation of New Jersey Application May 3, 1956, Serial o. 582,382 sclaims. cum- 118 This invention relates to blindstitch sewing machines and more particularly, to an improved work supporting mechanism for a blindstitch sewing machine.

It is an object of this invention to provide a work support on which the vwork fabric will be sustained in a uniform manner on each side of the stitching point.

It is also an object of this invention to provide a work support adapted to accommodate" uneven thicknesses of work fabric onopposite sides of the stitching point.

Another object-of this invention is to provide'a work support which will facilitate insertion of a work fabric to the stitching point of the sewing machine.

With the above and otherobjects and advantages in view as will hereinafter appear, this invention comprises the devices, combinations, and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

Fig. 1 represents an end elevational view of a blindstitch machine having my invention applied thereto;

Fig. 2 represents an enlarged end elevational view of the work arm and a fragment of the bracket arm with the work table and portions of the work supporting mechanism being in section;

Fig. 3 represents an enlarged top plan view of a portion of the work arm of Fig. 1 with the work sup porting feet and the ridge former being removed; and,

Fig. 4 represents an enlarged cross sectional view of the work arm taken substantially along line 4--4 of Fig. 1.

Referring more particularly to Fig. 1, this invention is applied to a blindstitch sewing machine having a conventional frame including a base 11, a work arm 12 pivotally supported, as at 13, on the base and extending transversely beneath the free extremity of a bracket arm 14. A throat plate 15 is fixed on the bracket arm beneath which the work fabrics are directed during the sewing operation. Carried for oscillatory movement in the bracket arm above the throat plate is a curved needle 16 and an orbitally movable looper 17 adapted to cooperate with the needle in the formation of stitches. An oscillatory ridge former 18 is carried in the work arm and is adapted to force a ridge of fabric upwardly through an aperture 19 in the throat plate and into the path of the oscillating curved needle. As is conventional in this type of blindstitch sewing machine, the work arm 12 is biased upwardly by a spring (not shown) into an operative position as determined by a stop arm 20 journaled on the pivotal support 13 and anchored in the machine frame. The stop arm abuts the front skirt 21 of the work arm to limit the height of the operative position of the ridge former.

The bracket arm also carries a Work feeding mechanism including a feed dog 22 which operates through the aperture 19 in the throat plate to engage and advance the fabrics in a direction to the left as viewed in Fig. 1. The work supporting mechanism of this invention is carried in the work arm 12 and is arranged to oppose 2 the feed dog 22 and also to maintain the work fabrics evenly at each side of the ridge-former.

The work supporting'mechanism' comprises a pair of work supporting feet 25 and 26 pivotally secured, as by shouldered pivot screws 27 one to each of a pair of links 28 and 29. Each of the links with a work supporting foot secured thereto constitutes a press'er unit, the units being disposed inside by side relation one at each side of the ridge former 18. The links 28 and 29 are journaled for turning movement on anelongated pivot' pin 30 fast in the work arm and, as best illustrated in Fig. 2', the links extend substantially in the direction of action of the feed dog 22 from the pivot pin 30 beneath the ridge former to'the pivot screws 27. Also jou'rnaled on the elongate pivot pin 30 is a U-shaped frame 31. A pair of coil springs 32--32, seate'd' each in a tapped'bore 33 and contacting an adjusting screw 34, bear upwardly against the frame 31. Upward movement of the frame under the action of springs 3232' is limited by an arm 35 which depends from the frame and is adapted to bear against stop screws 36 threaded into the work arm. The work arm has been broken away in Fig. 2 better to' illustrate this construction.

A lever 37 is fulcrumed on a shouldered screw 33 threaded into the base portion of the U-shaped frame 31 at a point between the links 28 and 29, as illustrated in Figs. 3 and 4. On each side of the fulcrum, the lever extends beneath lugs 39 and 40 depending one from each of the links 28 and 29, respectively. By means of the lever 37, the upward force of the coil springs 3232' is transmitted evenly to both of the work supporting feet regardless of the relative elevation of the feet. For instance, should a different number of plies of fabric be directed over each of the feet, as is conventional when blindstitching a folded hem in a fabric, the work supporting feet of this invention will automatically assume the proper elevation to accommodate the uneven thickness of fabric but the controlling forces exerted by the coil springs 32-32 will remain substantially equal on the work supporting feet and, therefore, the work fabrics will be directed evenly and consistently past the stitching point since the feed dog 22 will be opposed with substantially equal effort on each side of the stitched seam.

A two armed leaf spring 41 is secured to the base of the U-shaped frame 31 by a fastening screw 42 threaded into the frame between the links 28 and 29. Each free arm of, the leaf spring 41 extends beneath one of the links 28 and 29 and has for its purpose the maintaining of the work supporting feet at substantially the same elevation when the work arm 12 is lowered to facilitate removal or insertion of work fabrics in the sewing machine.

Insertion of work fabric into the machine is also facilitated by the arrangement whereby the work supporting feet links 28 and 29 extend substantially in the direction of action of the feed dog 22. Since the work fabrics are customarily inserted into the machine in this same direction, that is from right to left as viewed in Figs. 1 and 2,

the forces used to shift the fabrics to the stitching point arranged between said frame and said work arm biasing said frame toward said bracket arm, a lever fulcrumed on said frame between said links, and means on said lever operatively connecting said lever to each of said links, said means supporting said links in position upwardly inclined toward said bracket arm.

2. In a blindstitch sewing machine having a bracket arm, a free-ended work arm extending transversely beneath said bracket arm, stitch forming instrumentalities carried entirely by said bracket arm, and work feeding means carried by said bracket arm and adapted to feed work fabrics in one direction with respect to said bracket arm, means supporting beneath said bracket arm a work fabric to be blindstitched comprising, a pivot shaft carried in said work arm and disposed substantially normal to the direction of work feed, a pair of links journaled on said pivot shaft and extending from said pivot shaft in the direction of work feed, a pair of work supporting feet pivotally secured one to each of said pair of links, a frame journaled on said pivot shaft, spring means arranged between said frame and said work arm biasing said frame toward said bracket arm, and a lever operatively connected to each of said links and fulcrumed on said frame between said links.

3. In a blindstitch sewing machine having a bracket arm, a free-ended work arm extending transversely beneath said bracket arm, and stitch forming instrumentalities carried entirely by said bracket arm, means supporting a work fabric beneath said bracket arm comprising a fulcrum pin secured in said work arm, a U-shaped frame pivotally supported at each of the free extremities thereof on said fulcrum pin, a stop finger extending from said frame for engagement with said work arm to limit turning movement of said frame, a pair of coil springs arranged one at each side of said U-shaped frame and disposed between said work arm and said frame biasing said stop finger into engagement with said work arm, a pair of work engaging presser units each pivotally supported on said fulcrum pin between the free extremities of said U-shapedframe and each extending above said frame, and a lever fulcrumed on said frame between said presser units and operatively connected to each of said presser units.

References Cited in the file of this patent UNITED STATES PATENTS 

